August 5, 1966

MEMORANDUM for Chief, Research Projects Office

Subject: Preliminary flight report on X-15 flight 1-65-108 flown on July 28, 1966.

Summary

Flight 1-65-108 was flown essentially as planned by John B. McKay on July 28, 1966, to obtain data for X-15 follow-on experiments, (a) micrometeorite collection, (b) horizon scanner, (c) high altitude sky brightness, and (d) rarefied gas flow; also to measure electrical loads and evaluate the non-glare glass and stick kicker. Also a timing and coordination dry run for the PMR experiment was conducted on this flight and the results were very satisfactory.

The micrometeorite collector functioned normally except for interference by thermocouple wiring with the micro switch actuator gear as the collection surfaces rotated, resulting in only two of the six collection surfaces being exposed during flight.

The horizon scanner appears to have operated normally for a portion of the flight and then stopped for a reason not yet determined.

Both the high altitude sky brightness and rarefied gas flow experiments functioned normally.

Electrical load requirements of the auxiliary power units were measured and recorded during flight.

Evaluation of the non-glare glass and stick kicker was performed as planned.

The non-glare glass installed as the face plate of the alpha indicator made no observable difference in the pilot's reading this instrument.

Flight Profile

The radar track and profile for this flight are shown in figure 1 and a time history of the flight is shown in figure 2.

The launch was normal with approximately 20° of right roll being experienced. Engine light was also normal and 100% power was attained in 2.8 seconds. Rotation after launch was initially angle of attack = 13° for about 6 seconds, then lowered to angle of attack = 9° until the planned q was reached 3.6 seconds later than planned because the rotation was not the planned angle of attack = 11° rotation. Telemetry indicated q overshot slightly, then returned to the planned 34 for the remainder of the powered portion of the flight. The cockpit film indicated the q vernier was nulled at 34° throughout the boost phase.

Engine shutdown was to be accomplished at 5200 fps after 83 seconds of powered time. At his last checkpoint (4000 fps) the pilot observed that he was going high on profile and elected to shut the engine down early at 5150 fps indicated. As he started to make the shutdown engine burnout occurred. This point was at 85.2 seconds of powered time and a velocity of 5400 fps.

Peak altitude, due probably to the velocity overshoot, was 238,000 feet instead of the planned 220,000 feet.

A long period pitch oscillation was induced at engine shutdown and continued for 5.5 cycles until the pilot set the airplane up in the reentry alpha attitude. The pilot also indicated a problem in nulling yaw oscillations with BCS.

The reentry alpha during q buildup averaged the planned 20°. Beta also continued to build up during the reentry maneuver to approximately ±4°. This oscillation was damped as q increased and the pilot indicated it was not as bad as a yaw damper failure as experienced while flight planning in the simulator. The maximum q during the reentry was approximately 1600 psf.

Micrometeorite Collection:

This experiment was activated during the flight, by the pilot, at approximately 230,000 feet instead of the planned 150,000 feet. The experiment extended out of the right hand wing pod nose cone and started through its automatic timing cycle as anticipated. However during the exposure of the second of six collector surfaces the micro switch actuator gear caught on thermocouple wiring (figure 3) and stopped the automatic timing sequence.

During the descent through approximately 170,000 feet as planned the pilot initiated the experiment switch to retract. The experiment retracted into the wing tip pod normally and remained for the remaining duration of the flight.

The collector box has been returned to the experimenter for data evaluation.

Horizon Scanner:

Preliminary analysis of data indicate that the horizon scanner functioned as planned except for the photometer which did not operate because of a broken wire, and acquired good data for a period of approximately 4 seconds, after it was activated automatically. However, for some yet to be determined reason the experiment appears to have ceased to work properly after this short period of data acquisition.

Data are being analyzed by the experimenter in an effort to determine this apparent malfunction.

Sky Brightness:

No apparent problems were experienced in obtaining data for the high altitude sky brightness experiment. Preliminary analysis of data indicate this experiment functioned normally during the flight .

Data have been sent to the experimenter for a detailed analysis.

Rarefied Gas Flow:

There has been no indication of problems on the rarefied gas flow experiment (pace transducer) for this flight. Data are presently being analyzed.

Electrical Loads:

Data for the survey of the electrical loads on the APU's was recorded on this flight. The data are in the process of being analyzed in detail. A preliminary analysis indicates only a portion of the data recording channels operated during the flight.

Non-Glare Glass:

The non-glare glass was again installed as the face plate of the alpha indicator. The pilot did not report a glare to be a problem in the cockpit during the flight and did not comment on the effects of using non-glare glass as instrument face plates.

Stick Kicker:

A service pressure of 800 psi was utilized in the stick kicker system for this flight. The pilot indicated he thought he was aware of the stick kicker operating and pushed over at main gear touchdown. Due to a data recording malfunction, stabilizer position was not obtained for the stick kicker operation.

Inertial System:

During the prelaunch phase the Hdot indicator indicated 2,000 fps and could not be corrected. The cockpit film did show the indicator needle did move during the descent portion of the flight.

The pilot indicated and the cockpit film verified that the computer light came on during the powered portion of the flight. The pilot reset the system after shutdown and the light stayed out.

A preliminary analysis of the data indicate the computer dumped approximately 12 times in a span of 28 seconds. The longest period being two seconds.

Data are being further analyzed to try to determine the cause of the malfunction.

Instrumentation and Operational Discrepancies:

The pitch damper malfunctioned 14 seconds after shutdown and was reset two seconds later although ASAS was still on. ASAS was turned off 13 seconds later and SAS remained engaged.

Three minutes before launch the C Band Radar Beacon malfunctioned resulting in no data being obtained from the Tonopah tracking station. The malfunction is believed to be caused by a blown fuse.

After flight it was found that the 115-volt B-52 heater wires to the horizon scanner experiment were pinched together.

The following parameters did not calibrate during the data zero and calibrate sequences:

On telemetry the #1 APU turbine speed did not operate and the internal computer, computer inlet, and computer outlet temperatures read-outs had errors in them.

At the present these discrepancies are either being investigated to determine their cause or are being repaired in preparation for the next flight.
 

E. J. Adkins, Chief

X-15 Research Project Office